there was nothing to indicate that there had been tracks which had been skillfully covered up by whoever made them.
Again The Thinking Machine sat down on the box and studied his surroundings. Hatch watched him curiously. First he looked away toward the stone wall, nearly a hundred feet in front of him. There was positively no indentation in the snow of any kind so far as Hatch could see. Then the scientist looked back toward the house—one of the detectives had told him it was just forty-eight feet from the box—but there were no tracks there save those the detectives and Hatch and himself had made.
Then The Thinking Machine looked toward the back of the lot. Here in the bright moonlight he could see the barn and the clump of trees, several inside the enclosure made by the stone wall and others outside, extending away indefinitely, snow laden and grotesque in the moonlight. From the view in this direction The Thinking Machine turned to the other stone wall, a hundred feet or so. Here, too, he vainly sought footprints in the snow.
Finally he arose and walked in this direction with an expression of as near bewilderment on his face as Hatch had ever seen. A small dark spot in the snow had attracted his attention. It was eight or ten feet from the box. He stopped and looked at it; it was a stone of flat surface, perhaps a foot square and devoid of snow.
“Why hasn’t this any snow on it?” he asked Hatch.
Hatch started and shook his head. The Thinking Machine, bowed almost to the ground, continued to stare at the stone for a moment, then straightened up and continued walking toward the wall. A few feet further on a rope, evidently a clothes line, barred his way. Without stopping, he ducked his head beneath it and walked on toward the wall, still staring at the ground.
From the wall he retraced his steps to the clothes line, then walked along under that, still staring at the snow, to its end, sixty or seventy feet toward the back of the enclosure. Two or three supports placed at regular intervals beneath the line were closely examined.
“Find anything?” asked Hatch, finally.
The Thinking Machine shook his head impatiently.
“It’s amazing,” he exclaimed petulantly, like a disappointed child.
“It is,” Hatch agreed, cheerfully.
The Thinking Machine turned and walked back toward the house as he had come, Hatch following.
“I think we’d better go back to Boston,” he said tartly.
Hatch silently acquiesced. Neither spoke until they were in the train, and The Thinking Machine turned suddenly to the wondering reporter.
“Did it seem possible to you that those are not the footprints of Baby Blake at all, only the prints of his shoes?” he demanded suddenly.
“How did they get there?” asked Hatch, in turn.
The Thinking Machine shook his head.
On the afternoon of the next day, when the newspapers were full of the mystery, Mrs. Blake received this letter, signed “Three” as before:
“We hav the baby and will bring him bak for twenny fiv thousan dolers. Will you give it. Advertis as befour dereckted, YES or NOA.”
3
When Hutchinson Hatch went to inform The Thinking Machine of the appearance of this second letter late in the afternoon, he found the scientist sitting in his little laboratory, finger tips pressed together, squinting steadily at the ceiling. There was a little puzzled line on the high brow, a line Hatch never saw there before, and frank perplexity was in the blue eyes.
The Thinking Machine listened without changing his position as Hatch told him of the letter and its contents.
“What do you make of it all, professor?” asked the reporter.
“I don’t know,” was the reply—one which was a little startling to Hatch. “It’s most perplexing.”
“The only known facts seem to be that Baby Blake was kidnapped, and is now in the possession of the kidnappers,” said Hatch.
“Those tracks—the footprints in the snow, I mean—furnish the real problem in this case,” said the other after a moment. “Presumably they were made by the baby—yet they might not have been. They might have been put there merely to mislead anyone who began a search. If the baby made them—how and why do they stop as they do? If they were made merely with the baby’s shoes, to mislead investigation, the same question remains—how?
“Let’s see a moment. We will dismiss the seeming fact that the baby walked on off into the air and disappeared, granting that those tracks were made by the baby. We will also dismiss the possibility that the baby was with anyone when it made the tracks, if it did make them. There were certainly no other footprints but those. There were no footprints leading from or to that point where the baby tracks stopped.
“What are the possibilities? What remains? A balloon? If we accept the balloon as a possibility we must at the same time relinquish the theory of a preconceived plan of abduction. Why? Because no successful plan could have been arranged so that that baby, of its own will, would have been in that particular spot at that particular moment. Therefore a balloon might have been floated over the place a thousand times without success, and balloons are large—they attract attention, therefore are to be avoided.
“There is a possibility—a bare one—that a balloon with a trailing anchor or hook did pass over the place, and that this hook caught up the baby by its clothing, lifting it clear of the ground. But in that event it was not kidnapping—it was accident. But here against the theory of accident we have the kidnappers’ letters.
“If not a balloon, then an eagle? Hardly possible. It would take a bird of exceptional strength to have lifted a fourteenmonth child, and besides there are a thousand things against such a possibility. Certainly the winged man is not known to science, yet there is every evidence of his handiwork here. Briefly, the problem is—granting that the baby itself made the tracks—how was a baby lifted out of the relative centre of a large yard?
“Consider for a moment that the baby did not make the tracks—that they were placed there by some one else. Then we are confronted by the same question—how? A person might have fastened shoes to a long pole and rigged up some arrangement of the sort, and made the tracks for a distance say of twenty feet out into the snow, but remember the tracks run out forty-eight feet to the box you say.
“If it would have been possible for a person to stand on that box without leaving a track to it or from it, he might have finished the tracks with the shoes on a pole, but nobody went to that box.”
The Thinking Machine was silent for several minutes. Hatch had nothing to say. The Thinking Machine seemed to have covered the possibilities thoroughly.
“Of course, it might have been possible for a person in a balloon to have put the tracks there, but it would have been a senseless proceeding,” the scientist went on. “Certainly there could have been no motive for it strong enough to make a person invite discovery by sailing about the house in a balloon even at night. We face a stone wall, Mr. Hatch—a stone wall. It is possible for the mind to follow it only to a certain point as it now stands.”
He arose and disappeared into an adjoining room, returning in a few minutes with his hat and
